Clean air, clear viewsTighter environmental standards make a difference
To understand just how much air quality has improved in the region, just ask Jim Renfro, the air quality specialist with Great Smoky Mountains National Park.
Renfro started working with the park in 1984 and has seen direct evidence of the damages caused by air pollution — and how much a situation can change in 15 years.
“Improvement in the haziness index is incredible,” Renfro said. “It used to be hazy days were the norm. If they got a good, clear glimpse of the mountains, people would notice that. Now hazy days are the exception. Haziness has improved 150 percent since the late 1990s, which is great news.”
The change is the result of numerous public policy changes — new federal standards, the N.C. Clean Smokestacks Act, improvements at Tennessee Valley Authority plants, tougher fuel standards and cleaner vehicle emissions.
Changes made by power plants and in vehicle emissions — the two biggest producers of nitrogen oxides — made the largest impact on reducing the ground-level ozone, which is harmful to human, biological and aquatic life.
The 70 percent reduction of sulfur dioxide across the Southeast since 1990 is credited with the reduced particulate matter in the air and is credited for increased visibility in the park, Renfro said. The particulates also posed a threat to people who work in or visit the park because the fine particles can penetrate deep into the lungs and cause numerous problems.
“Ozone levels are down 29 percent from the late ‘90s,” Renfro said, “and particulate matter is down 40 percent. These are huge decreases and are good news for our health, for sure.”
During the 1980s, air quality problems became a focus in the park as acid rain (caused by sulfur dioxide and nitrogen oxides) was found to be damaging forests, plants and streams.
The problem worsened in the ‘90s, Renfro said, but as the standards changed, some improvements, notably haze, were noticed rather quickly.
For instance, on a hazy day in the ‘90s, the visibility from the Look Rock air quality station on the park boundary at the North Carolina-Tennessee line was just 9 miles. Now, visitors can see for an average of 47 miles on many days.
High elevation woes
While there are no polluting industries located within park boundaries, high-elevation air quality monitoring sites are most often the ones in violation of standards. That’s because mountains and ridge tops “stick up like a sore thumb,” Renfro said, and trap all sorts of emissions.
“It rains more, there are higher winds and is more cloud water in the mountains,” he said, “and the air contains sulfates and nitrates that are deposited.”
While improvements have been recorded in visibility, the data is inconclusive on how long it will take to overcome damage to streams and plant life within the park.
A number of park streams are on the national water quality impairment list, and the acid rain that has fallen over the years has changed the chemical makeup of both soils and streams, Renfro said.
Modeling is currently under way to study the recovery issue, and within a year of so, Renfro said experts will have a better idea of whether it will take decades or a century to restore the ecosystem to its unpolluted state.
“We know systems are responsive to damage, and preliminary results show there is an ability to recover if we can reduce sulfur dioxide and nitrogen oxides,” he said. “But some systems may been harmed beyond repair.”